Cutting-off tool



P 1943-v D. T. BROWNLEE 2,329,872

CUTTING OFF TOOL Filed Dec. 31., 1941 Fig.4

INVENTOR bul wwn .T @MumQw Patented Sept. 21, 1943 2329,8721 eummosonn'roon t v Dalinan Templeton Brownl'ee, Indianapolis, Ind. V Applieationljecemben s1, 1941,8eriaf Nm425,247 cla ms; (elite-iron l This invention relates" to an improvedft'ool of the variety "which is used in lathes'fs'crewf ma chines and the like forcuttin'goif pieces-from ba'rsof steel-and othermaterial. I I "*In use the tool is secured to a' cross slide orswingingarm of the machine andsl'owly f d-into a-rotating bar of thematerial from which apiece isto'becutoff. ,1 Such tools are commonly known as -:cutting of tools and their performanceisrelatively unsatis factor-y. As commonly c'onstruct'edthey are quite fragile and must be carefully handled and fre quently sharpened otherwise thecut willbe rough and the-tool'may seize and'bebrok'en;

"The usual cutting ofi t oolconsistsof'a holder provided with aslot and clamping means to secure a straight blade; The-bladeis'usuallya relatively long and thin barof high speed steel, either rectangular or keystone shapedin cross section. The portion of theblade that does the cutting-protrudes from the holder andis commonly' ground so as to obtain relief on=-the sides and a liner chip curler on 'the'top' edge. relieving; the blade is ground so as; to taper on both sides from the cutting edge back to the holder and if theblade is of recta'ngular cros'ssection the grindingmust also I reduoezthe thickness fromtop to bottom. This leavesthe cuttingedge of the blade thicker than'the restlof the-protruding portion and eliminates: binding; but unfortunately brings the minimum cross: section oi the blade to the edge of the holder where the bending moment is greatest. 'Asathe; end at the blade is ground-01f in sharpening the thickness of the entire relieved portion is gradually reducedlas the relief must be run back a corresponding amount. Finally the areaof the cross section oi the blade at the edge of the holder becomes insuilicient and either" the=relieved portion breaks off or is purposely broken off by the operator. Ob- Viously a new cutting edge and relief must be round on the blade.

In cutting off steel and certain alloys it is well known that a concave contour on top of the blade causes the chip to curl and shear ofi more easily, thereby prolonging the life of the cutting edge of the blade and reducing the load on both blade and machine. Tests have shown that this device, known as a chip curler or lip, may increase the amount of cutting as much as four times per sharpening. However, each time a straight blade is sharpened the chip curler must be ground back further and deeper and soon the cross sectional area at the bottom of the chip curler becomes insuificient and either breaks at this point ground away, broken or speed steehthe usual material for'bl'ades; is ex'-' or is -broken 'off Icy-the operator. A new-cutting edge, chip curler and relief-must beground to" restore blade-to original condition; As the cross s'ectionalarea-reduction due to relief grinding'and 1 chip curler grinding is additiveitwill be readily understoodwhythe number'of sharp'enihgs per 7 blade is not large.

Altogether the useof straightcutting ofi' blades is lwastef-ul and expensive. Considerable time and skill are required to grindftheproper relief and contour and in practical use more than-one'hall scrapped. Ashigh pen'sive andka seriousishortage' of' this material that this 'waste b'c-elimi'n ated.

appear-shear at hand, it isof utmost It is an object of the invention to provide acutting high speed steel or other cutting material.

; Another object of the invention is to provide a" cutting olf toolthat'ma y. be "quickly and correctly sharpened-"by" ameohanic oflimited es:

peri'ence. V V gE-Another object :of the invention is to provide a cuttingofi tool.- that-has aninh'erentchip curler;

,Another object of the invention is" to provide a-cutting oiitooi that provides substantial sup-- portforthe-blade. .7 Other objects of the invention will appear from thefollowingdescription taken in connectionnwith the; draw-ing; ,wherein.I have illustrated a pre ferred embodiment of my invention; and :in which? y r Figure 1 is a side elevation of thecomplete tool.

- Figure 2is'an'end view of the holder without the blade. t Figure 3 isa sideelevation of the-blade. Figure 4 is an end view thereof.

In thedrawing the holder leis provided with a concave cylindrical blade seat II in which a number of small square t'eeth'are cut. The blade I! is in the form of an interrupted ring with teeth on its outer periphery matching those of the seat I I in the holder. A'bout midway of the seat H the holderis provided with a slot l2 that divides the seat into two portions and bifurcates the front end. of the holder into two branches or arms.

Perpendicular to the slot is a clamp screw l 6 for the purpose of drawing'the two portions of the seat H slightly closer together thereby securely holding the blade I 1.

l0 isrecessed at I 3 and I4 in order thickness of the blade seat II to The holder to reduce the that of the thinnest part of the blade IT. The

periphery of each of these recesses is that of a importance off tool that isjeconomi'cal in the use? of circular arc scribed from a center located at the cutting edge I8 of the blade II. The front end of the holder l0 below the blade seat is sloped at an angle, preferably degrees from the vertical, the purpose of which will be presently explained.

The blade I! is keystone shaped in cross section from end to end with the thick end of the section inward and varies uniformly in average thickness from end to end, and has its greatest thickness at the cutting edge I8 and its least thickness at the point 19. While the entire blade may be made of steel, for greater economy I prefer to make the .15

major portion of the blade from inexpensive one piece of high speed 1 "'in the holder, an interrupted ring shaped blade provided with low carbon steel and braze thereto a relatively v small piece of high speed steel or other expensive cutting material.

and after tooth cutting and operations, to out each ring into two equal parts, each part constituting ablade. i

In use the blade 11 is slipped into the holder [El with a sidewise motion with the cutting end 2| protruding slightly from the holder and wi h the teeth on the blade interlocking those of the holder. The clamp screw I6 is now tightened to securely hold the blade. When sharpening is required the end of the bladeis brought up against the flat side of a grinding wheel at an angle, usually 10 degrees from the verticaLgAs a guide to correct sharpening the front: end 55 of the holder is formed to this same angle.- After several sharpenings the blade ;may: be slipped out of the holder seat with a sidewise motion and rotated a tooth to advance the cutting edge to a new positicnfor additional;sharpenings. This may be repeated from time to time until the high speed steel piece ZEl is almost entirely used up. It will be observed that'due'to the construce tion of the blade and its ,mountinga concavetop surface for curling the chip is maintained throughout the life of the blade; that ,owing'wto its keystone cross section and lengthwise tapering hickness, the bladecontinues to have relief until it is used up; that the one simple operation of grinding the front end 2! of the blade parallel to the front end l5 of the holderassures the correct angle for the cutting edge; that the blade is well supported behind and below and thereby very resistant in use to deflection and breakage. [although the invention has been described in connection withi a tool suitable for use in an ordinary lathe, the shape and proportions-of the tool and its parts may be greatly modified as conditions require. The inventiontherefore is to be limited only as indicated by the scope of thea'ppended claims; I, r it Foreconomical manu-y facture I prefer to make up as complete rings other machining pro e ha -0 holder, 2. blade adapted to fit said seat, an arm of the holder extending toward the cutting edge of said blade, recesses in one or both sides of the arm reducing the thickness thereof to approximately that of the blade with the periphery of said recesses approximating arcs of circles scribed from a center located near said cutting edge of the blade, i

2. A cutting off tool for lathes, screw machines and the like including a holder, a concave seat a cutting edge and adapted to fit said seat, the thickness of the holder being reduced by recessesin one or both sides to apthe thinnest part of the blade with the periphery of said recesses approximatingarcs of circles scribed from a center located near said cutting edgeof the blade, I

:3. A' cutting off tool"forlathes, 'screw machines and the like including alholder a blade, a por-, tion of the holder bif urcatedjinto arms disposed in the planeof the blade, a seat in the arms adapted rtoli old the blade, with the thickness of thearms adjacent the blade not exceeding the thickness of the blade and means to clamp the arms and secure the blade in the seat.

4. A cutting'ofifltooljfor lathes, screw machines and the like including aholder, an interrupted ring shaped blade, a portionof theholder bifurcated into arms, a concave seat in; the arms adapted to hcld'the blade, the thickness of the arms adjacent the blade not exceedin the thickness of the blade andmeans to clamp the arms and secure the blade in the seat, r i

a 5. A cutting or? tool for 1athes.,-screw machines and the like 'an interrupted ring shaped blade with a toothedperipheryLa portion of the holder bifurcated into, arms, a toothed concave cylindrical seat in the armsadapted to fit the blade in meshing engagement, the thickness .of the arms adjacent the blade not exceeding the thickness of the blade andmeans to pull the arms closer together and secure theblade in the seat.

6. A'cutting ofi tool for lathes, screw machines and the like including av holder, a blade having an endinclinedto form a cutting edge, a portion of the holder. bifurcated into'arms disposed in the plane of the blade, a seat in the arms adapted to hold the blade, the thickness of the arms adjacentthe blade not exceeding the thickness off.the :bladejone arm'exten'ding to near said inclined end-0f the blade and terminating substantially parallel therewith and means to clamp the arms andsecure the blade in the seat.

DALMAR "rnMrLn'ron 'BROWNLEE. 

